Standardization of b values allows improved interstudy comparisons on the diagnostic accuracy of diffusion-weighted MR breast examinations. PurposeTo compare the diagnostic quality of diffusion-weighted (DW) imaging schemes with regard to apparent diffusion coefficient (ADC) accuracy, ADC precision, and DW imaging contrast-to-noise ratio (CNR) for different types of lesions and breast tissue. Materials and MethodsInstitutional review board approval and written, informed consent were obtained. Fifty-one patients with histopathologic correlation or follow-up performed with a 3.0-T MR imager were included in this study. There were 112 regions of interest drawn in 24 malignant, 17 benign, 20 cystic, and 51 normal tissue regions. ADC maps were calculated for combinations of 10 b values (range, 0–1250 sec/mm2). Differences in ADC among tissue types were evaluated. The CNRs of lesions at DW imaging were compared for all b values. A repeated-measures analysis of variance was used to assess lesion differentiation. ResultsADCs calculated from b values of 50 and 850 sec/mm2 were 0.99 × 10−3 mm2/sec ± 0.18 (standard deviation), 1.47 × 10−3 mm2/sec ± 0.21...

Purpose: To retrospectively correlate changes in fractional anisotropy (FA) and mean diffusivity in gliomas at diffusion-tensor magnetic resonance (MR) imaging with the degree of tumor cell infiltr...

Purpose: To evaluate proton magnetic resonance (MR) spectroscopic imaging with high spatial resolution for preoperative grading of suspected World Health Organization grades II and III gliomas. Mat...

Rationale and Objectives This study compared metabolic differences in the frontal brain of depressed patients versus age- and sex-matched controls using proton magnetic resonance spectroscopy and absolute quantification of metabolites (NAA, Cr, Cho, mI) at 3 Tesla. Methods Short-echo-time stimulated echo acquisition mode (TE/TM/TR=20/30/6000 milliseconds) was applied in the prefrontal region of 17 depressed patients and 17 age- and sex-matched controls. Metabolic ratios, ie, N-acetyl-aspartate/creatine (Cr), choline/Cr, and myo-inositol/Cr, and absolute concentrations (using internal water as a reference together with LCModel-based spectra fitting) were calculated and compared between groups and published reference data. Results Metabolic ratios showed significantly lower N-acetyl-aspartate/Cr (P = 0.016/0.006, left/right), choline/Cr (P = n.s./0.016), and myo-inositol/Cr (P = 0.022/0.026) for depressive patients versus controls. However, depressive patients showed significantly higher absolute concentrations of Cr (P = 0.017/0.0004) compared with controls with no differences in all other metabolites estimated. Conclusions The authors demonstrate that absolute quantification of metabolite concentration is essential in properly identifying pathologic differences of brain metabolites in depression.